ssh2/example/simple/ssh2_exec.c

/*
 * $Id: ssh2_exec.c,v 1.1 2009/05/05 12:27:02 bagder Exp $
 *
 * Sample showing how to use libssh2 to execute a command remotely.
 *
 * The sample code has fixed values for host name, user name, password
 * and command to run. Change them to something suitable.
 *
 */

#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <ctype.h>

#include <libssh2.h>


static int waitsocket(int socket_fd, LIBSSH2_SESSION *session)
{
    struct timeval timeout;
    int rc;
    fd_set fd;
    fd_set *writefd = NULL;
    fd_set *readfd = NULL;
    int dir;

    timeout.tv_sec = 10;
    timeout.tv_usec = 0;

    FD_ZERO(&fd);

    FD_SET(socket_fd, &fd);

    /* now make sure we wait in the correct direction */
    dir = libssh2_session_block_directions(session);

    if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
        readfd = &fd;

    if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
        writefd = &fd;

    rc = select(socket_fd + 1, readfd, writefd, NULL, &timeout);

    return rc;
}

int main(int argc, char *argv[])
{
    const char *remotehost  = "127.0.0.1";
    const char *commandline = "uptime";
    const char *username    = "user";
    const char *password    = "password";
    unsigned long hostaddr;
    int sock, i;
    struct sockaddr_in sin;
    const char *fingerprint;
    LIBSSH2_SESSION *session;
    LIBSSH2_CHANNEL *channel;
    int rc;
    int exitcode;
    int bytecount = 0;

#ifdef WIN32
    WSADATA wsadata;
    WSAStartup(MAKEWORD(2,0), &wsadata);
#endif
    (void)argv;
    (void)argc;

    hostaddr = inet_addr( remotehost );

    /* Ultra basic "connect to port 22 on localhost"
     * Your code is responsible for creating the socket establishing the
     * connection
     */
    sock = socket(AF_INET, SOCK_STREAM, 0);

    sin.sin_family = AF_INET;
    sin.sin_port = htons(22);
    sin.sin_addr.s_addr = hostaddr;
    if (connect(sock, (struct sockaddr*)(&sin),
                sizeof(struct sockaddr_in)) != 0) {
        fprintf(stderr, "failed to connect!\n");
        return -1;
    }

    /* We set the socket non-blocking. We do it after the connect just to
        simplify the example code. */
#ifdef F_SETFL
    /* FIXME: this can/should be done in a more portable manner */
    rc = fcntl(sock, F_GETFL, 0);
    fcntl(sock, F_SETFL, rc | O_NONBLOCK);
#elif defined(HAVE_IOCTLSOCKET)
    ioctlsocket(sock, FIONBIO, &flag);
#else
#ifdef WIN32
    u_long mode = 1;
    ioctlsocket (sock, FIONBIO, &mode);
#else
#error "add support for setting the socket non-blocking here"
#endif
#endif

    /* Create a session instance */
    session = libssh2_session_init();
    if (!session)
        return -1;

    /* Since we have set non-blocking, tell libssh2 we are non-blocking */
    libssh2_session_set_blocking(session, 0);

    /* ... start it up. This will trade welcome banners, exchange keys,
     * and setup crypto, compression, and MAC layers
     */
    while ((rc = libssh2_session_startup(session, sock)) ==
           LIBSSH2_ERROR_EAGAIN);
    if (rc) {
        fprintf(stderr, "Failure establishing SSH session: %d\n", rc);
        return -1;
    }

    /* At this point we havn't yet authenticated.  The first thing to do
        * is check the hostkey's fingerprint against our known hosts Your app
        * may have it hard coded, may go to a file, may present it to the
        * user, that's your call
        */
    fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_MD5);
    fprintf(stderr, "Fingerprint: ");
    for(i = 0; i < 16; i++) {
        fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
    }
    fprintf(stderr, "\n");

    if ( strlen(password) != 0 ) {
        /* We could authenticate via password */
        while ((rc = libssh2_userauth_password(session, username, password)) ==
               LIBSSH2_ERROR_EAGAIN);
        if (rc) {
            fprintf(stderr, "Authentication by password failed.\n");
            goto shutdown;
        }
    }
    else {
        /* Or by public key */
        while ((rc = libssh2_userauth_publickey_fromfile(session, username,
                                                         "/home/user/"
                                                         ".ssh/id_rsa.pub",
                                                         "/home/user/"
                                                         ".ssh/id_rsa",
                                                         password)) ==
               LIBSSH2_ERROR_EAGAIN);
        if (rc) {
            fprintf(stderr, "\tAuthentication by public key failed\n");
            goto shutdown;
        }
    }

#if 0
    libssh2_trace(session, ~0 );
#endif

    /* Exec non-blocking on the remove host */
    while( (channel = libssh2_channel_open_session(session)) == NULL &&
           libssh2_session_last_error(session,NULL,NULL,0) ==
           LIBSSH2_ERROR_EAGAIN )
    {
        waitsocket(sock, session);
    }
    if( channel == NULL )
    {
        fprintf(stderr,"Error\n");
        exit( 1 );
    }
    while( (rc = libssh2_channel_exec(channel, commandline)) ==
           LIBSSH2_ERROR_EAGAIN )
    {
        waitsocket(sock, session);
    }
    if( rc != 0 )
    {
        fprintf(stderr,"Error\n");
        exit( 1 );
    }
    for( ;; )
    {
        /* loop until we block */
        int rc;
        do
        {
            char buffer[0x4000];
            rc = libssh2_channel_read( channel, buffer, sizeof(buffer) );
            if( rc > 0 )
            {
                int i;
                bytecount += rc;
                fprintf(stderr, "We read:\n");
                for( i=0; i < rc; ++i )
                    fputc( buffer[i], stderr);
                fprintf(stderr, "\n");
            }
            else {
                fprintf(stderr, "libssh2_channel_read returned %d\n", rc);
            }
        }
        while( rc > 0 );

        /* this is due to blocking that would occur otherwise so we loop on
           this condition */
        if( rc == LIBSSH2_ERROR_EAGAIN )
        {
            waitsocket(sock, session);
        }
        else
            break;
    }
    exitcode = 127;
    while( (rc = libssh2_channel_close(channel)) == LIBSSH2_ERROR_EAGAIN )
        ;
    if( rc == 0 )
    {
        exitcode = libssh2_channel_get_exit_status( channel );
    }
    printf("\nEXIT: %d bytecount: %d\n", exitcode, bytecount);

    libssh2_channel_free(channel);
    channel = NULL;

shutdown:

    libssh2_session_disconnect(session,
                               "Normal Shutdown, Thank you for playing");
    libssh2_session_free(session);

#ifdef WIN32
    closesocket(sock);
#else
    close(sock);
#endif
    fprintf(stderr, "all done\n");
    return 0;
}